Carbogen is

Match the following types of hydrides in List-$I$ with their examples in List-$II$.

List-$I$ (Type of hydride)	List-$II$ (Example)
$(A)$ Electron precise	$(i)$ $SiH_4$
$(B)$ Saline	$(ii)$ $H_2O$
$(C)$ Electron deficient	$(iii)$ $MgH_2$
$(D)$ Electron rich	$(iv)$ $B_2H_6$

Lithium hydride can be used to prepare other useful hydrides. Beryllium hydride is one of them. Suggest a route for the preparation of beryllium hydride starting from lithium hydride. Write chemical equations involved in the process.

Hydrogen behaves as an oxidising agent when it reacts with:

The correct statements among $(a)$ to $(d)$ regarding $H_2$ as a fuel are:
$(a)$ It produces fewer pollutants than petrol.
$(b)$ $A$ cylinder of compressed dihydrogen weighs $\sim 30$ times more than a petrol tank producing the same amount of energy.
$(c)$ Dihydrogen is stored in tanks of metal alloys like $NaNi_5$.
$(d)$ On combustion,the values of energy released per gram of liquid dihydrogen and $LPG$ are $142$ and $50 \ kJ,$ respectively.

Given below are two statements: one is labelled as Assertion $A$ and the other is labelled as Reason $R$.
Assertion $A$ : Hydrogen is the most abundant element in the Universe,but it is not the most abundant gas in the troposphere.
Reason $R$ : Hydrogen is the lightest element.
In the light of the above statements,choose the correct answer from the options given below: